Eight of the 12 host cities for this year's delayed European Championship have said they will allow spectators at matches based on projections of an improving Covid-19 situation, UEFA said on Friday, but the remaining four risk being dropped as hosts altogether.
Munich, Rome, Bilbao and Dublin have all been given until April 19 to release their plans to let fans in, with European football's governing body saying "final decisions will be made on that date regarding the staging of matches in those four venues".
UEFA's executive committee will meet then and there is the possibility that it could strip hosting rights from those four cities and give their matches to other existing host venues.
Earlier this week the Football Association of Ireland admitted it was "not in a position at this point to provide assurances on minimum spectator levels" in Dublin, but the country is preparing to take tentative steps towards lifting its current lockdown which has been in place since December.
Bilbao is understood to be hoping to allow 13,000 fans inside the 53,000-capacity San Mames, but that is based on strict conditions laid out by authorities which the Spanish Football Federation said will make it "impossible" to admit spectators.
The city of Munich indicated on Tuesday that it could only let fans inside the Allianz Arena if the health situation at the time allows, but the Italian government has given the green light for supporters to attend in Rome.
Last month UEFA president Aleksander Ceferin made it clear he did not want any matches played "in front of empty stands" at the Euro, which will be played from June 11 to July 11 after being postponed by a year due to the pandemic.
The number of spectators allowed in stadiums nevertheless looks set to vary considerably, with Saint-Petersburg and Baku confirming they will allow crowds at 50 percent of capacity and Hungarian capital Budapest aiming to allow 100 percent capacity "but with strict stadium entry requirements for spectators."
Hungarian Prime Minister Viktor Orban said Friday that by the beginning of the Euro all those who registered for vaccination in Hungary would have received it and would therefore be eligible to attend.
-Everyone who is registered will definitely have been vaccinated, and with their vaccination card will have the opportunity to take part in this event- he said.
UEFA said Amsterdam, Bucharest, Copenhagen and Glasgow will allow between a quarter and a third of full capacity, while London "has confirmed a minimum capacity of 25 percent for the first three group matches and round of 16 match".
That leaves open the possibility that more fans will be able to attend the remaining matches at Wembley Stadium, which will stage both the semi-finals and the final.
UEFA said each host city had been left to make its own decision on the number of fans permitted to attend games and that "many factors" had been taken into consideration, notably the roll-out of vaccinations.
Supporters with tickets hoping to travel to Budapest will not have to quarantine on arrival, UEFA said, but will need to present two negative Covid-19 test results.
In Azerbaijan, fans with tickets in Baku will be allowed to attend and will not need to quarantine as long as they are citizens or residents of Turkey, Switzerland or the United Kingdom as well as the countries who reach the quarter-finals.
Bucharest will also let ticket holders in with a negative test and a guarantee to stay less than three days.
However, the body said "no exemptions will be made for ticket holders elsewhere". All fans with tickets can therefore choose to hand them back by April 22 and get a full refund.
